A numerical approach for analysis of structure of lower-permittivity insulating nanoporous composite

This paper attempts to show the effective porous-structure of the nanoporous-silica/epoxy composite for lower-permittivity insulating material by using numerical analysis. The theoretical analysis indicated that the reduction of electric field enhancement at delamination defect of electrode/epoxy interface by more than 25 % required the relative permittivity (ε_r) of less than 3.0 of nanoporous-silica/epoxy composite in the case that the ε_r of conventional insulating material was 4.0. From the dielectric mixture formula, it is estimated that ε_r of less than 3.0 of nanoporous-silica /epoxy composite required the particle porosity of more than 23 %. Based on the Pashcen´s law, it is estimated that the discharge inception field of nanopore with the size of less than 0.05 μm could be higher than the dielectric breakdown strength of 100 kV/mm in epoxy composite material, that is, the nanoporous-silica/epoxy composite with nanopore size of less than 0.05 μm could have the voltage-endurance.